Just about any community college offers sculpture classes and workshops. Some offer short term sessions on evenings and weekends for non-student types as well. There are also a number of small groups that meet here and there. What part of town are you looking for? What medium? If your desire is to work figuratively, you might look into the Los Angeles Academy of Figurative Art << laafa.org >>. If you are working with a traditional artist's budget (aka: $0) ask around your local art supply store to see if there are any informal group workshops or supplier product demos.
Good luck!

If you want an accredited program and Orange County is not too far, check out the Laguna College. Raymond Persinger and Marianne O'Barr both teach sculpture there. Also check out their teaching website SculptNow.com to see their students work. They also teach at other locations on occasion.